Magnetron



March 18, 1941. w. EsPE 1 2,235,517

MAGNETRON Filed Nov. 19, 1938 ATTORNEY Patented Mar. 18, 1941 UNITE-D g STATES PATENT oFFlcE MAGNETRON Application November 19, 1938, Serial No. 241,358

. In Germany November 25, 1937 11 claims. (c1. 2504275) The invention relates to discharge devices and particularly to discharge devices inwhich the 'flow of electrons emitted by the cathode is subjected to the influence of a magnetic field.

An object of the invention` is to provide a discharge device having `its discharge path subject to the influence of the magnetic field in which the magnetic means producing such eld is replaceable and is easily adjustable.

Other objects and advantages of the invention will be apparent from the following description and drawing, in which:

Fig. 1 is a view, partly in cross-section and partly in elevation, of a preferred'embodiment of the invention. v I

Fig. 2 is a modification of certain parts disclosed in Fig. 1.

Certain types of tubes utilize a magnetic field applied to the discharge path between the anode and cathode. One type, forinstance, is that of a vacuum tube for producing short wave oscillations having an electrode system consisting of an anode and a cathodeconcentrically arranged. The magneticv eld for such a tube has been provided by a permanent or electro-magnet terminating adjacent the container walls.

It is one of the objects of my invention to provide magnetic means which are located most effectively in providinga magnetic field for the discharge space and are, in addition, easily adjusted as to eld strength and, also, are easily replaced if necessary.

In Fig. 1, the container l is preferably of annular shape comprising an insulated portion I preferably of glass and having a hollow body 6 forming the central opening therethrough. This hollow body 6 is of non-magnetizable material which will seal to the glass walls of the outer container I. The walls of the hollow Ibody 6 may be of metal such as copper or may be of ceramic, glass or other non-metallic material.

The electrode system preferably comprises a cathode I0 placed about the hollow body 6 and preferably concentric therewith. In the figure, the cathode is disclosed in the form of a continuous coil around the hollow body 6. Various other forms of cathode may, of course, be used such as a wire, zig-Zagging longitudinally back and forth around the circumference of the hollow body. For short wave work, the anode structure preferably consists of two anode segments 2 and 3 connected to the lead-in wires 4 and 5. The segments are placed concentric with the cathode and hollow body as disclosed. Inside of the hollow body E, is a permanent magnet 1 in the form of a rod-shaped magnet, occupying the central space of the hollow body 6. The rod 'l can be easily replaced by withdrawing it from the hollow body 6 if necessary. Inplace of removing the permanent magnet, the rod l -15 can be remagnetized by the coil 9 and yoke 8 disclosed in the drawing. The parts 8 and 9 are not used when the device is in operation.

If an electro-magnet, in place of a permanent magnet, isutilized, I prefer to use the structure 10 illustrated in Fig. 2. The annular envelope 20 encloses, by means of the hollow lbody or pipe 24, an electro-magnet 2|. The pipe 24 preferably has pole-shoes for the closure members of the hollow body, with the screw-threaded connection 15 disclosedfor closing off the inside of the central opening of the envelope. These closure membersr 22 and 23 also preferably have the central projections therein to provide the adjustable clearance 25 and 26 to the ends of the core 20 of the electro-magnet 2|. The magnetic field produced by theelectro-magnet 2l can be varied in its strength by changing the air space 25 and 26 between the pole-shoes and the electro-mag'- net. This is done by screwing the pole-shoes 25 on the pipe 24 towards and away from the ends of the core of the electro-magnet.

In case the central pipe or hollow body 24 is of copper, the cathode and electro-magnet should be carefully insulated therefrom. This 30 can be done by having a thin ceramic coating on the surface of the copper adjacent the location of the cathode and electro-magnet or by baking on ceramic powder to form such an insulative layer. 35

The closure members 22 and 23 may have ventilating openings, as disclosed, for the passage of a liquid or gaseous cooling medium through the hollow body. Air cooling may also -be achieved by exposing an opening through the 40 hollow body of Fig. 1 or Fig. 2, through the blast of a cooling air current.

For the sake of clearness, the cathode and anode have not been illustrated in Fig. 2, but they may take any form desired, including the 45 forms disclosed in Fig. 1.

The magnetic eld of the magnet 'l or electromagnet 2| extends from one end of the structure through the discharge space tothe other end of 'l or 2|. The non-magnetic material of 50 the casing 6 or 24 will aid in spacing the magnetic lines of force into the discharge space. The adjustment of the pole shoes 22 and 23 in Fig. 2 will strengthen or weaken the magnetic eld in the discharge space. 55

The current through the cathode wire I0 will produce also a magnetic iield around the cathode Wire that will react with the magnetic eld produced by the magnet 'I or electromagnet 2|. The resultant eld will control the shape of the path taken by the electron from the cathode IS toward the anodes 2 or 3. The anodes 2 and 3 are preferably connected in the usual oscillator circuit.

It is apparent that many modifications may |be made in the form, number, and arrangement of the various elements disclosed in the preferred embodiments illustrated in the drawing. Accordingly, only such limitations are intended on the following claims as are necessitated by the prior art.

I claim:

1. A discharge device comprising a container enclosing a hollow portion, means for producing a magnetic field in said hollow portion, a cathode within said container surrounding said hollow portion and anode structure within said container surrounding and symmetrical with said cathode.

2. A discharge device comprising a container having a vacuum tight portion enclosing a longitudinally extending space accessible from the exterior of the container, a cathode within the vacuum tight portion and on the wall of said container enclosing the longitudinally extending space and anode structure surrounding and symmetrical with said cathode.

3. A discharge device comprising a container having a Vacuum tight portion enclosing a longitudinally extending space accessible from the exterior of the container, a cathode within the vacuum tight portion and on the portion of the Wall of said container immediately enclosing the longitudinally extending space and anode structure symmetrical with said cathode and magnetic means within said longitudinally extending space and removable therefrom.

4. A discharge device comprising a container having an anode and a cathode, said container having nonmagnetic walls enclosing a space adjacent said anode and cathode, magnetic means in said space and closure members of magnetizable material completely closing said space.

5. A discharge device comprising a container having an electrode system including an anode and, cathode, said container enclosing a space concentric with said electrode system and having openings to the exterior of said container, magnetic means within said space and closure members of magnetizable material completely closing said openings.

6. A discharge device comprisinga container having an electrode system including an anode and cathode, said container enclosing a space adjacent to said electrode system and having openings to the exterior of said container, magnetic means within the space and closure members of magnetizable material located at said openings andadjustable in spacing with said magnetic means.

7. A discharge device comprising a container having an electrode system including an anode and cathode, said container enclosing a space concentric with said electrode system and having openings to the exterior of said container, magnetic means Within the space and closure members of magnetzable material located at said openings and adjustable in spacing with said magnetic means.

8. A discharge device comprising a container of annular shape having anode and cathode, an electro-magnet within the central openingV and closure members of magnetizable material completely closing said central opening.

9. A discharge device comprising a container of annular shape having anode and cathode, an electro-magnet within the central opening and closure members of magnetizable material for said central opening adjustable with respect to said electro-magnet.

10. A discharge device comprising a containerv of annular shape having anode and cathode, an electro-magnet Within the central opening and closure members of magnetizable material com pletely closing said central opening, said anode and cathode being symmetrical with said central opening.

11. A discharge device comprising a container having an anode and cathode therein, a tubular member extending through saidV container and sealed thereto and adapted to contain magnetic means, and closure members making a screwthreaded connection with sai-dtubular member, said tubular member being of non-magnetizable material andsaid closure members being of magnetizable material.

WERNER ESPE. 

